Blower slows after time, comes back if turned off for a while

Nissan Rogue forum - Includes Nissan Qashqai and Nissan Dualis as well.
ObsessiveDad
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Car: 2015 Nissan Rogue SL

Blower slows after time, comes back if turned off for a while

Postby ObsessiveDad » Wed Aug 03, 2022 9:54 am

Having a weird issue with the fan/blower for the HVAC system. After about an hour of driving the "wind" drops to where there is barely air coming out of the vents...when this happens it doesn't matter what setting is changed, mode, fan speed, auto, dual, heat/AC...still no "wind". However, you can still hear the fan speed change if you change the speed setting...it just doesn't affect how much air comes out of the vent.
If you turn off the hvac completely and leave it for 5-10 minutes it comes back full speed.
I've read about 2 stage resistor? (VBC?) could that be it? Doesn't seem like a fuse, motor or relay issue to me. Any other suggestions where to start troubleshooting?

I HAVE recently recharged my AC system, vacuumed it first, ran a can of oil because those tester things told me to, then recharged with 134a. It cools fine and the system has held pressure since the recharge. But I'm pretty certain I was having the blower issue before the recharge, however it's only an issue on long drives so I tend to forget about it in between, so it's been lurking for a while now.
It's a 2015 SL AWD.

thanks


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VStar650CL
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Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

Re: Blower slows after time, comes back if turned off for a while

Postby VStar650CL » Wed Aug 03, 2022 10:16 am

Most likely you have a stuck TXV valve that's causing the A/C evap to ice up. Ventilation air must pass through the evap regardless of whether the system is set for cold or heat, on heat the evap simply doesn't chill it much before it goes through the heater core. When a TXV sticks open (even partly), it causes the evap to gradually ice-over and block incoming flow. Turning the car briefly off allows the ice to melt and restores function.

ObsessiveDad
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Joined: Wed Aug 03, 2022 5:43 am
Car: 2015 Nissan Rogue SL

Re: Blower slows after time, comes back if turned off for a while

Postby ObsessiveDad » Wed Aug 03, 2022 10:30 am

Thanks! Just did a quick search on servicing that, doesn't seem to be too complicated but definitely will take some time. Now for the million dollar question, if that IS the probelm and I continue to operate the system for a while (either on short or long drives) am I risking damaging more components? My gut says yes.

Before I go evacuating the system again and pulling the glove box and all that...would the evap "ice up" be noticeable from the outside, as a way of confirming that's the issue?

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VStar650CL
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Re: Blower slows after time, comes back if turned off for a while

Postby VStar650CL » Wed Aug 03, 2022 10:46 am

No harm, it's just temporarily an icemaker instead of an A/C. Changing out the TXV doesn't require any excavation inside the car. The only thing required is removing the cowl, then the TXV is right there where the A/C lines enter the firewall. Popping the cowl isn't difficult, two 14mm nuts for the wiper arms, six plastic clips holding the cowl cover, three 10mm's holding down the wiper assembly, four 13mm's and about eight 10mm's holding the cowl. On a good day I can have one loose in about 5 minutes. Use new o-rings on both sides and lube them with either PAG or Vaseline. If you're good and have power tools, evacuating and leak-checking the system will take longer than replacing the valve.

ObsessiveDad
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Car: 2015 Nissan Rogue SL

Re: Blower slows after time, comes back if turned off for a while

Postby ObsessiveDad » Thu Aug 04, 2022 4:05 am

Oh, I must have been reading about the wrong vehicle...what I read said the expansion valve (that's the txv correct?) was INSIDE another component, the compressor if I remember correctly. I'll have to find it in the service manual. Thanks again!

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VStar650CL
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Re: Blower slows after time, comes back if turned off for a while

Postby VStar650CL » Thu Aug 04, 2022 4:40 am

Yep, the Rogue expansion valve (and most other Nissans) is a plug-assembly located at the entrance to the evap. That's true on most cars, but on some it's a separate in-line piece and on a few it's integrated with the evap so you need to replace the whole thing. The gen2 Rogue is easy, see HA-44 here:
https://www.nicoclub.com/service-manual ... 5%2Fha.pdf

ObsessiveDad
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Re: Blower slows after time, comes back if turned off for a while

Postby ObsessiveDad » Mon Aug 08, 2022 8:19 am

Perfect, thank you!

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VStar650CL
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Re: Blower slows after time, comes back if turned off for a while

Postby VStar650CL » Mon Aug 08, 2022 9:18 am

:dblthumb:

ObsessiveDad
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Re: Blower slows after time, comes back if turned off for a while

Postby ObsessiveDad » Tue Aug 30, 2022 1:49 pm

Before I order a new one, if that was the problem would it still happen without the ac running in the first place? Your explanation says that cold or warm air must pass through it, but would it require the AC to be running to ice up in the first place? Did the same drive without AC for the first time in a while, and sure enough...about an hour in the blower went down to almost nothing.

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VStar650CL
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Re: Blower slows after time, comes back if turned off for a while

Postby VStar650CL » Tue Aug 30, 2022 2:26 pm

Yes, depending on what "off" means. The gen2 Rogue has a "swash plate" compressor that never cycles, it simply goes to minimum volume on the swash plate when the A/C load is small or zero. So if the A/C switch was on or the HVAC was set to defrost or foot-defrost, the compressor would run in the background even if the system was nominally "off". It's also possible that the high speed on your VBC is overheating. The gen2's with Auto A/C have a weird two-speed blower control that uses different driver FET's for low and high speeds, so it's possible the high speed FET is going open-circuit after the blower has been running awhile. The definitive test would be to put the system on vent, floor, or bi-level with the A/C button unlit to assure the compressor is off. If it still acts up, the VBC is probably your culprit and not the TXV.

ObsessiveDad
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Car: 2015 Nissan Rogue SL

Re: Blower slows after time, comes back if turned off for a while

Postby ObsessiveDad » Wed Aug 31, 2022 3:48 am

I guess it's definitely the high speed control then. That's exactly what happened, it was on bi-level, ac never activated, no defrost.
And the VBC is what people also call the blower motor resistor correct? The one up behind the radio, that you have to remove the pedals to replace?

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VStar650CL
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Re: Blower slows after time, comes back if turned off for a while

Postby VStar650CL » Wed Aug 31, 2022 4:40 am

On a gen2 it can be reached without pulling the pedal, but pulling the pedal may be easier if you haven't done one before. It's squeezed against the firewall up high on HVAC housing. Good news is, the Auto ones are just held in by a single screw. See HAC-8 here:
https://www.nicoclub.com/service-manual ... %2Fhac.pdf

Plug your VIN into NissanPartsDeal to make sure you get the right part number, the Auto and Manual VBC's are way different. Even if you buy the VBC elsewhere, using the OE part number when searching will save you a lot of grief.

ObsessiveDad
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Car: 2015 Nissan Rogue SL

Re: Blower slows after time, comes back if turned off for a while

Postby ObsessiveDad » Tue Sep 06, 2022 4:47 am

Will do, thanks. After the wheel hub ordeal I've learned to triple confirm parts from now on.


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